1. Field of the Invention
The present invention relates to a vehicle traveling state determining apparatus that can determine whether or not, for example, a driver's awoken state is impeded during driving, so that the driver is falling asleep at the wheel.
2. Description of the Related Art
In recent years, with the development of a road network and an increase in leisure hours, there have been an increasing number of opportunities for driving a car. The driver is desired to be always physically and mentally stable during driving. However, the driver may drive a car while conscious of his or her bad physical condition. In this case, during long continuous driving, the driver's fatigue keeps piling up and his or her concentration lowers. Consequently, the driver's awoken state may be impeded and the driver may become sleepy.
To prevent this, a vehicle is provided with a camera that picks up a frontal image that allows white lines on roads to be recognized to determine whether or not the vehicle is traveling in a zigzag line. This system thus determines whether or not the driver is falling asleep at the wheel. If the result of the determination is affirmative, the system gives a warning (for example, Japanese Patent No. 3039327).
In this document, the apparatus picks up images of traveling zone partitioning lines and on the basis of the images, determines whether or not the vehicle is traveling in a zigzag line. However, there is another method of recognizing white lines on the opposite sides of a road to determine whether or not the vehicle is traveling in a zigzag line. However, with this method, it is impossible to determine whether or not the vehicle is traveling in a zigzag line if the entire road surface is covered with snow or if even without snow, there are no white lines on the opposite sides of the road.